Various types of rotating machine require cooling. A subset of such rotating machinery includes those fabricated by metallurgically bonding a hub portion to a ring portion. In these examples, the hub portion includes an outer circumference that is bonded to an inner circumference of the ring portion, thus forming a circumferential bond line at the interface between the outer circumference of the hub and the inner circumference of the ring. Hub/ring fabrication of rotating machinery is desirable because it allows for the use of different alloys for the hub portion and for the ring portion, among other reasons.
Non-limiting examples of such rotating machinery that requires cooling, whether they be bonded along a bond line or not, include axial turbines and compressors, radial turbines and impellers, and others as will be appreciated by those having ordinary skill in the art. FIGS. 1 and 2 are provided for purposes of illustrating some of these examples. More particularly, FIG. 1 is a perspective view of an axial turbine rotor bladed disk 100 as known in the prior art. The turbine rotor bladed disk 100 has a hub 102, a ring 104, and a plurality of blades 106 on the ring 104 that are configured to withstand a wide range of temperatures. Generally, the hub 102 is disk-shaped and surrounded by the ring 104. The blades 106 extend radially outward from the ring 104. The hub 102 and ring 104 are diffusion-bonded together along bond line 103 and are generally formed from superalloy materials. Both components may be formed from the same material or may be formed from materials that vary in composition. The hub 102 and/or ring 104 may be cast into equiaxed, directionally solidified, or single crystal components.
Additionally, FIG. 2 is an isometric view of a radial turbine 200 as known in the prior art. As can be seen in FIG. 2, radial turbine 200 includes a hub 266 and a ring 256, with the ring 256 include a plurality of blade segments 258, which are circumferentially spaced around and extend radially outward on the ring 256. A bond line 253 illustrates the bonding region between the hub 266 and the ring section 256. As with the axial turbine example of FIG. 1, the radial turbine example of FIG. 2 has the hub 266 and the ring 256 diffusion-bonded together along the bond line 253 and are generally formed from superalloy metals, which may be the same or different.
During operation, rotating machinery is often exposed to elevated temperatures. In the case of the exemplary rotating machinery noted above in FIGS. 1 and 2, such elevated temperatures may be caused by the impingement of hot gasses upon the machinery, or by the compression of gasses as a function of the machinery's operation. As the temperature of the rotating machinery increases, some areas of the rotating machinery, which in some examples may include the bond line (e.g., bond line 103 or 253), are less able to withstand structural loads placed on the rotating machinery. Beyond a certain temperature, the rotating machinery could fail at these areas during operation. Further, exposure to high temperatures may cause accelerated low-cycle fatigue (LCF) of the rotating machinery.
FIG. 3 is provided to illustrate this problem in the context of the radial turbine 200 shown in FIG. 2. More particularly, FIG. 3 shows a segment 200A of the radial turbine 200, with its forward end 285 at left, and it rearward end 286 at right. During operation, hot gasses are directed toward the leading edge of blade segment 258. These hot gasses cause a temperature maximum at the forward end of bond line 253, which is illustrated by oval 290. Such temperature maxima at the bond line 253, as noted above, may undesirably cause structural failure or accelerated LCF of the radial turbine.
As such, it would be desirable to provide rotating machinery that is not susceptible to structural failure or accelerated LCF due to exposure to elevated temperatures. To accomplish the foregoing aim, it would be desirable to provide cooling directed at the heat-susceptible areas of the rotating machinery, which, in the case of rotating machinery including a hub portion bonded to a ring portion, may be a bond line, in order to minimize the temperatures to which such heat-susceptible areas exposed. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.